Must the engine used in F1 tests confirm to regulations?

Is it required to use an engine that fills the rules and regulations required for racing. Can you bypass the racing limit of fuel flow during testing?

Before the season starts the car can differ from the regulations. They are very close to the racing spec for that year as using something that is not permitted in races would yield little benefits. FIA is not regulating fuel flow during testing, but similarly to engine specs - the benefits for the season would be minimal.